Process of preparing printers&#39; overlays and underlays.



UNITED srerns .srsn'r FFlC 'EDUARD LANKESAND KARL SCHWARZLER, OF MUNICH, GERMANY.

PROCESS OF PREPARING PRINTERS OVERLAYS AND UNDERLAYS.

Specification of Letters Patent.

Patented June 30, 1908.

Application filed August 2, 1906. Serial N 0. 828,953.

Improvements in Processes of Preparingv Prlnters Overlays and Underla'ys; and we do hereby declare the following to be a full, clear, and exact description of the invention,

such aswill enable others skilled in the art to which it appertains to make and use the same.

The present invention relates to an improved process for the reduction of relief underlays and overlays cm a suitable surface capable of being etched, and specifically, from a chalk mass or the like, upon an underlayer of paper material. The reliefs are roduced by etching and may be employs in the printing press as an underlay for the printing plate, but generally, however, as an overlayupon the pressure cylinder or tympan sheet 1n order to regulate the pressure of the ress to emphasize the gradations of tone in t e picture, and to protect the fine parts of the printing plate so as to insure a great number of im ressions before wearing it out.

Since, in t e carryin out of the known etching processes, the depth of stratum removed in laces by etching and also the differences o the reliefs and the printing eflect depend as well upon the shorter or longer time of-etchin as also upon the strength of the etching" so ution and, further, upon the more or less vigorous movement during the etching and the flowing of the etching bath, therefore, it has been diliicult or imcpossible to produce with safety a determine height of the relief or to etch several reliefs of the same height. This evil'beoomes especially disadvantageous when several such consesequently high reliefs are to be used as under- I'ays or overlays at the same/time in one press, in which case they must first, by a tedious'levelingprocess be brought to an equal height for printing.

The present improved process has for its further object, therefore, to provide a means by which the de th of the etching and thereby' the height 0 the relief can be gaged exactly, during the etchin so that it is easy, by nterrupting the etc ing process at the right time, to obtain reliefs o exactly equal heights. This is'obtained by the following arrangements of the coatings of the relief mass to be etched upon the bahe. The

stratum to be etched is coated in a uniform thickness upon. a differently colored base or u on a base whose upper surface only is d1fierently colored, as for example, a white stratum u on a base colored red, or reversely. s an alternative, the etching ground itself is coated upon the base in several thin strata of different colors. As an etching ground one may employ for exam le chalk, lime in combination with a binding matter, as a base, paper material. However,

there may also be employed as an etching round other mineral material capable 0 being attacked by acid, in combinat on with a binding material. Forchalk, a solution of chlorid of lime is very suitable as an etching means.

The coating of the etching strata and. the working out of the relief can be done either upon one side of the paper base, or, alsb, for the pur ose of increasing the action, upon both si es at the same time. In the second case, the printing plate or electrotype in connection with which the relief is to be employed-as an underlay or overlayis placed in a printing press, and upon a tym an sheet fastened upon the printing cy in or of the press, the illustration is printed several times one over the other, exactly registerin after an inkin each time with a resist in r. The printing plate is again freshly inked, the paper sheet, provided on both sides with an etching ground, is laid upon the freshl printed tympan sheet and run throug the press under pressure, whereby there is obtained an impression from the printing plate upon the front of the etching groun ing ground can be placed in 'a 2% etching bath, which consists of water with the addition of dissolved chlorid of lime, in order to develop the relief.

The etching bath which is kept in motion continuously in order that the front and rear sides of theprinted plate shall be simultaneously attacked is allowed to act only until at the bright places or at the unprinted margin at the outer bordenof the picture, the'upper stratum is etched away and the differently colored stratum under it or the paper base itself appears. Owing to the translucent properties of the sheet and the tinting of the strata, the progress of the etching may be advantageously observed by transmitted light as in the development of a negative in the photographic dark room.

The darker portions of the picture, remain untouched by the etching fluid because they are protected by the resist ink while the half tones are deepened more or less corresponding to their tone values, and the high lights are etched through to the under layer where-.

be exactly opposed to the same details of the printing plate. The ositioning of the relief overlay is greatly facilitated by the inherent semi-transparent qualities of the paper base and chalk relief portions, by means of which the relative positions of the overlay and impression can be visually ascertained. The transparency of the overlay can be further enhanced by oiling. lief sheet is placed beneath the thin printing plate or electrotype, between the same and the block on which it is mounted, correspondence being secured by cutting the two to conform or providing guide lines or points to secure exact register. When used as an underlay, the thin rinting plate will be firmly backed up in t e darker printingportions by the relief portions of the underlay While the high lights will have a space at the rear wherethe upper surface of the underlay is etched away, and as a consequence the difierences in tone of the printed picture will be emphasized in printing. The same result is secured as an overlay, the relief portions sustaining the paper on which the prlntin is being done against the pressure of the dar er portions of the printing plate, while the deeper portions of the overlay permit the a er to yield at the high lights, and in the aff tones in proportion. Not only is a more vivid and clear impression thus secured but the life of the printing plate is prolonged as the more delicate portlons and details of the picture are-protected. The chalk relief sheet has further artistic value in itself, as the paper base and chalk strata etched to varying degrees of thickness and so placed that a strong light shall pass therethrough,

As an underlay the reconstitute a beautiful translucent picture in which all the details and tones of the typographic print are brought out, not by the use of ink but solely by the differences in amount of light permitted to pass through the varying thicknesses of the picture. The use of differently tinted strata in the etching ground, moreover, tints the picture, when viewed as a transparency, more or less, as the stratum is etched away to a greater or less extent. i

, Having thus described our invention, What we claim as new is:

1. An improved method of preparing reliefs, which consists in printing with a resist ink upon a sheet of etchable material consisting of differently tinted homogeneous strata, and etching the surface of the sheet until an underlying stratum appears.

2. An improved method of preparing printers relief underlays and overlays, which consists in taking an impression from the printing plate upon a sheet of chalk material consisting of differently colored strata by means of a resist ink, etching the sheet, and placing the etched relief in register with the printing plate.

3. An improved method of preparing printers relief underlays and overlays, which consists 1n taking an lmpression from the printing plate upon a sheet of etchable material consisting of differently colored strata,

by means of a resist ink, etchingthe sheet until an underlying stratum appears, and then placing the etched relief in register with the printing plate.

4. An improved method of preparing printers relief underlays and overlays, which consists in taking an impression from the printing plate upon a sheet of paper having an etchable surface consisting of a diflerently colored stratum by means of a resist ink, etching until an underlying stratum appears and then placing the etched relief in register with the printing plate.

5. An improved method of preparing printers relief underlays and overlays, which consists in printing heavily by means of theprinting 1plate and -a resist ink u on the tympan s eet, laying over the heavi inked impression a sheet of etchable materlal con sisting of differently colored strata, operating the press to obtain an impression from the plate upon the face of the etchable sheet and from the tympan sheet upon the back of the etchable sheet, etching the sheet and placing the etched relief sheet in register with the printing plate.

6. An improved method of preparing printers relief underlays and overlays,which consists in printing heavily by means of the printing late and a resist ink .upon the tympan s set, laying over the thus heavily inked impression a sheet of etchable material consisting of differently colored strata, op

I again positioning t e etched re ief sheet in contact with the tympan sheet in exact register with the impression thereon and in opposition to the printing plate.

7. An improved method of preparing printers relief underlays and overlays, which consists in printing-heavily. by means of the late and a resist ink upon the tympan s eet, laying over the thus heavily inked impression a sheet of etchable material consisting of a pa er'base with differently coloredsuper ose chalk strata, operating the press to o tain an impression from the late upon the face of the etchable sheet and om the tympan sheet upon the back of the etchable sheet, etching the sheet until an underlying stratum ap ears, and again positioning the etched re ief sheet in contact with the tympan sheet and in exact register with the impression thereon and in oppositio to the printing plate.

A sheet of translucent material com posed of difierently tinted strata bearing an etched re resentation, the deeper incut portions an the higher relief portions corresponding respectively to the lights and shadows represented.

In testimony whereof we hereunto affix our signatures in the presence of two Witnesses.

EDUARD LANKES;

KARL SCHWARZLER.

Witnesses:

ULYSSES J. BYWATER, LoUrs MUELLER. 

